The ultimate purpose of the proposed study is to increase our understanding of how the motor cortex controls movement and subsequently to contribute toward the better treatment of human motor dysfunctions. The specific aims during the coming years are to explore the neuronal mechanisms underlying the motor learning in higher mammals. During the past grant period, we have discovered that tetanic stimulation of the sensory cortex produces long term potentiation (LTP) of synaptic potentials in the motor cortex in cats raising the possibility that this cortico-cortical (CC) input participates in motor learning and memory. During the coming years, following experiments will be carried out. The purpose of these experiments are to-examine 1) whether all CC input to and from the motor cortex produces LTP by delivering tetanic intracortical microstimulations to the motor cortex or other cortices projecting to the motor cortex, 2) whether this input actually participates in motor learning by training the monkey for a new motor skill with and without the projection area to the motor cortex. Then we will examine 3) whether all CC input in the cerebral cortex can produce LTP and 4) whether the pyramidal tract also produces LTP. Besides, we will examine 5) whether LTP is the only plastic change resulting from repeated activity of the sensory cortex. The last experiment will be done by delivering repetitive burst stimulations to the sensory cortex chronically and then counting the number of synapses at the terminal branches of CC fibers in the motor cortex. The results will hopefully open a new field for the study of motor learning and memory in higher mammals including the primate.